The city staff and a building advisory committee want to repeal a 2008 law requiring separate gray-water plumbing in new Tucson homes.

They say the gray-water systems are significantly costlier than once thought, and that no homebuyers have taken advantage of the systems.

Some City Council members, along with environmentalists, are resisting the proposal, saying the gray-water requirement is critical to prepare Tucson for future droughts.

David Godlewski, Southern Arizona Home Builders Association president, said that he can't say for certain, without talking to individual builders, that home prices would drop with repeal. The builders' cost, typically passed onto consumers, can be $800 or more. Homeowners must pay more for additional equipment.

But he added, "Ultimately in today's market, every dollar that can be saved in a government requirement will be to the benefit of homebuyers."

Opponents, however, also don't like how city staff members handled the repeal proposal, by not including the array of interest groups that shaped the 2008 law.

The repeal had been slated to come up last week at a City Council study session as part of a broader package of amendments to other construction-related codes. City Councilman Paul Cunningham objected to repeal and got discussion delayed to Dec. 4.

Cunningham blasted the proposal as shortsighted and done with inadequate public discussion. Unlike the gray-water proposal in 2008, this one was not brought to the council separately. The original law passed after months of discussions by a 14-member committee representing the Audubon Society, SAHBA, a commercial developer, plumbers, Habitat for Humanity, the American Institute of Architects, the Sierra Club, the Arizona Builders Alliance and the Sonoran Institute.

By contrast, the repeal proposal came from a seven-member committee consisting largely of construction-related representatives: a homebuilder, an architect, an engineer, and a mechanical contractor, among others.

"Water conservation is a key element in Tucson's survival. To slip this in … is civic irresponsibility of ludicrous proportions. I will not support any code change that removes the gray-water program," Cunningham said.

The city's Development Services director, Ernie Duarte, didn't return calls seeking comment about the issue or how staffers handled it.

The Tucson-Pima County Joint Code Committee voted unanimously last summer to recommend repeal. The committee did it in open meetings with public comment invited and encouraged, a committee member said.

"It's very costly and right now we're not aware of any city permit that has been issued for a homeowner to put in a gray-water system," said Ken Cawthorne, a mechanical engineer on the building code committee. "There's a considerable amount of maintenance involved. Plus, I'd prefer we have additional water in our system to flush the solids through from the toilets - if we pipe the gray water separately, I'm afraid we will have more frequent clogs in our houses."

City Councilman Steve Kozachik supports repeal, having been told by homebuilders that on small, inner-city lots, the gray water equipment can undercut foundations. "If no one is using the gray-water plumbing, we should do what we can to help the housing industry," he added.

As the ordinance now stands, builders of new homes must install two indoor plumbing systems: one to pipe "black water" from toilets, dishwashers and kitchen sinks into the sewer system, and another to pipe gray water from bathroom sinks, showers and bathtubs to the outdoors. From there, it's up to homeowners to install additional piping, a pump, and storage tanks, so they can use the gray water on their landscaping.

Backers said that a homeowner who used all possible tools to put their gray water on plants could save about 13,000 gallons of water a year. That's about 12.5 percent of a typical Tucson homeowner's annual water use.

When the law passed, authorities estimated it would cost homebuilders about $500 a home to comply.

SAHBA's Godlewski, however, said that for a single-story home today's cost is about $600 to $800, and for a two-story home the system costs builders $800 to $1,000.

So far, city building officials say that no buyers of about 800 new homes that received permits since the law took effect in June 2010 have come in for separate permits needed to install gray water plumbing.

Godlewski said he doesn't think homebuyers will hop on board once the housing market recovers, either.

Tucson Water - which hasn't taken a stand on the repeal proposal - has had a $200 rebate program for homeowner gray water systems since January 2011. But so far only 10 families - all owners of existing homes - have obtained the rebates.

This month, the staff and Citizens Water Advisory Committee recommended that the city boost the rebate to $1,000 to get more takers. A homeowner's share of installing gray water plumbing costs about $475 to $1,375, depending on the system, Tucson Water says.

But the lack of homebuyers using the gray-water systems today isn't the point -this rule is for the future, countered Tucson Audubon Society director Paul Green, who sat on the 2008 committee.

"When Central Arizona Project water becomes scarce, and we're not going to have water to put on our landscapes," is when gray water will be needed, Green said. "How crazy is it to pump water 350 miles uphill from the Colorado River to put it onto your landscape?"

"It's very costly and right now we're not aware of any city permit that has been issued for a homeowner to put in a gray-water system."